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57 Stone Compaction - When??
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57 Stone Compaction - When?? By  TJAMBS

Posts: 4

9/20/2011 10:09:43 AM

Does anyone know a good reference on 57 stone and its requirements for compaction versus non compaction under slabs, or pipes, or whereever it is being used, for the various parts of the country and the various stone types??  Or, is this just something each local geotech firm needs to address depending on where in the country you are located??


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57 Stone Compaction - When?? By  Dominick Kasmauskas

Posts: 1

9/20/2011 11:11:43 AM

From what I've read....57 is self compacting and to plan against granular soils above working into the stone which will increase more settling. Use fltering fabric to protect against this. 

Leaks from the pipes you are protecting may be another issue in loosening the stone as well as seismic issues.

Watch sidefill material also...there may be migration considerations there also...more fabric.

Again...the ablove is only what I have taken from items I've read....not my professional experience.

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   Edited By Dominick Kasmauskas at 9/20/2011 11:12:32 AM.

57 Stone Compaction - When?? By  Uncle Bob

Posts: 174

9/20/2011 12:08:31 PM


Welcome to the forum.  This is a bit (a big bit) over my head; when you specify 57 stone; and the requirements should vary according to local soils and codes; however you can go here and these Engineers are discussing your subject;


I don't find anything specific in the 2009 IBC or IRC; referencing 57 stone compaction in Chapter 19 of the IBC or Chapter 5 of the IRC.

Hope this helps,

Uncle Bob

Retired Texas Combination Inspector. Location Oklahoma.

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   Edited By Uncle Bob at 9/20/2011 12:14:29 PM.

57 Stone Compaction - When?? By  TJAMBS

Posts: 4

9/20/2011 1:51:33 PM

Guys - thanks for input thus far.  I have been on that engineer site and read many comments.  I have also computed the maximum difference in density between loose and rodded 57 stone.  It is just that it is used so widely, I thought somewhere someone may have written something definitive as a result of field testing, compaction methods, etc.  I believe we are going to start hiring a geotechnical firm to test the 57 stone in place when we are using it more than about 12" thick below salbs.  It is field testable I understand but not using standard methods.  I understand from geotech firm(s) it is a special process but can be reasonably relied upon to know the status of the stone before a slab is placed on it.  Thanks again for inputs through 12:50 p.m., 9/20/2011.


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57 Stone Compaction - When?? By  Richard Allen

Posts: 2

10/4/2011 12:13:59 PM

No. 57 stone is an easily consolidated material but it is not self-consolidating.  Uncompacted or dumper deposits of No. 57 stone can settle about 1" per foot of thickness.  No. 57 stone should be placed in lifts and consolidated using conventional compaction techniques.  It is very obvious when the stone is consolidated and locked into place, so visual inspection is adequate.

The appropriate lift thickness depends on the type of compaction employed.  For light sled tampers, the loose lift thickness should be no more than 6 inches.  For hoe rams and remotely controlled rollers, the loose lift thickness should be on the order of about 8 inches.  For full-size vibratory (operator driven) rollers, the lift thickness could be up to 12 inches. 

Richard L. Allen, P.E.
Sr. Geotechnical Engineer
Bowser-Morner, Inc. - Toledo, Ohio

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